The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera, Chrysomelidae), is an important insect pest of maize in North America and Central and Eastern Europe. In Central Europe, the larvae emerge in May and its three instars feed intensively on maize roots in June, causing plant lodging that leads to a loss of economic yield. A three-year field experiment (2016–2018) was conducted to compare the effectiveness i) of soil-applied granular insecticide based on the active ingredient tefluthrin, ii) of maize seeds dressed with thiacloprid, and iii) entomopathogenic nematodes Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae, product Dianem) against WCR larvae. An additional treatment with alcohol ethoxylate (i.e., soil conditioner) mixed with entomopathogenic nematodes was performed in 2017 and 2018 to check for any increase of entomopathogenic nematodes’ effectiveness. Field tests were carried out in two fields infested naturally with a WCR pest population, one in Bučečovci (Eastern Slovenia) and the other in Šmartno pri Cerkljah (northern Slovenia), exhibiting dissimilar pedo-climatic conditions and soil pest densities. The treatments were performed in five replicates per experiment in each year. The efficacy of the treatments was very similar at both locations, despite the approximately five-fold lower WCR soil pest densities in northern than in eastern Slovenia, as well as being constant over time. The largest number of WCR beetles was observed in the negative control, followed by that of beetles subjected to thiacloprid treatment (insignificant decrease taking into account the entire three-year dataset). Treatments with tefluthrin (44.1 ± 11.7%), H. bacteriophora (46.2 ± 7.4%), and H. bacteriophora + alcohol ethoxylate (49.2 ± 1.8%) significantly decreased the numbers of emerging beetles. Treatments of thiacloprid, H. bacteriophora, and H. bacteriophora + alcohol ethoxylate additionally led to significantly increased maize plant weights. Furthermore, entomopathogenic nematodes were able to persist in maize fields for almost five months at both experimental locations in silty and sandy loam soils. It was concluded that the control of WCR larvae in maize using the entomopathogenic nematode H. bacteriophora is as effective as a tefluthrin treatment, and could thus offer a sustainable Diabrotica v. virgifera biological control management option in Europe.

中文翻译：

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细菌性杂种细菌性腹泻（Rhabditida：Heterorhabditidae）和合成杀虫剂对西部玉米根虫幼虫控制的田间效果评估

西部玉米根虫（WCR），即Diabrotica virgifera virgifera LeConte（鞘翅目，葫芦科），是北美，中欧和东欧的重要玉米害虫。在中欧，幼虫在5月出现，三龄幼虫在6月以玉米根为食，导致植物倒伏，导致经济单产下降。进行了为期三年的田间试验（2016-2018年），比较了i）基于有效成分tefluthrin的土壤施用颗粒杀虫剂的有效性，ii）噻虫啉包衣的玉米种子的杀虫效果，以及iii）昆虫病原线虫的细菌性杂种优势。抵御WCR幼虫的Poinar（Rhabditida：Heterorhabditidae，产品Dianem）。在2017年和2018年，采用了乙氧基醇乙醇（即土壤改良剂）与昆虫病原线虫混合的另一种处理方法，以检查昆虫病原线虫的效力是否有所增加。在两个自然受WCR害虫侵染的田地上进行了田间试验，一个在Bučečovci（斯洛文尼亚东部），另一个在Šmartnopri Cerkljah（斯洛文尼亚北部），其人为气候条件和土壤虫害密度不同。每年每个实验重复进行五次重复处理。尽管北部地区的WCR土壤虫害密度比斯洛文尼亚东部地区低大约五倍，而且随着时间的推移保持不变，但在两个地方的处理效果都非常相似。在阴性对照中观察到最大数量的WCR甲虫，其次是接受噻虫啉处理的甲虫（考虑到整个三年的数据集，无明显减少）。tefluthrin治疗（44.1±11.7％），H. bacteriophora（46.2±7.4％）和H. bacteriophora +乙醇乙氧基化物（49.2±1.8％）显着减少了新出现的甲虫的数量。噻虫啉，幽门螺杆菌和幽门螺杆菌+乙醇乙氧基化物的处理另外导致玉米植物重量显着增加。此外，昆虫病线虫能够在粉质和沙质壤土的两个实验地点在玉米田中持续近五个月。结论是，使用昆虫病原线虫H. bacteriophora控制玉米中的WCR幼虫与tefluthrin处理一样有效，因此可以提供可持续的Diabrotica v。virgifera 欧洲的生物防治管理选项。